The discovery, in 1935, that the percentages of the oxygen isotopes were not everywhere constant was a definite disadvantage to using oxygen as a base for atomic weights
When the question was changed to "Which one of the following could be the atomic weight
New Columbia Encyclopedia, at atomic weights
An atomic weight
is considered as an outlier when the corresponding continued fraction representation provides a mass value outside the interval "atomic mass [+ or -] standard deviation".
Because isotopes of hydrogen are unevenly distributed in nature, "the standard atomic weight
that used to be in the table wasn't actually the atomic weight
of any occurrence of hydrogen," says Michael Wieser, an associate professor at the University of Calgary and secretary of the commission.
the atomic weights
of all chemical elements are whole-number multiples of the atomic weight
For those of you who have forgotten your periodic table, that element, Ru, has an atomic weight
of 44; it is a member of the platinum group--which explains why, when asked what the paint costs, Mark Waiter, a product manager for Sverdrup Technology, which provides asset management of the climatic wind tunnels and cold rooms at the Dearborn Proving Ground for Ford, simply states that it is a whole lot more expensive than the house paint that you might buy at K-mart.
Dense pigments or other additives can induce further errors, explains Fishman, because beta gauges become more composition-sensitive as the atomic weight
of the target material goes up.
Nearly 99 percent of the carbon on Earth has an atomic weight
of 12 - except in this hen and her eggs.
A note by Mendeleev, in March of 1869, was published and sent in Russian and French to scientists, titled "Experience of Systems of Elements Founded on Their Atomic Weights
and Chemical Similarity" (with "atomic weight
" to be understood as "atomic mass" here and in the future).
The foundations of mass spectrometry date back nearly 200 years to John Dalton, who proposed that all matter is composed of elements, that the number and types of atoms corresponded to the exact number and types of elements, and that all elements have a measurable physical property, atomic weight
But mass fraction averaging is based on atomic weight
, which is the total mass of the protons, electrons and neutrons.
Errant assumptions led to some large errors--Dalton miscalculated oxygen's atomic weight
as 7 instead of 16, for example.
In October 2006 in was reported that element 118 had been synthesized in Dubna (Russia), with atomic weight
Ion implanters are used because of their ability to implant selected elements, called dopants, into the silicon wafers by bombarding them with a precisely controlled beam of electrically charged ions of specific atomic weight